CEFR - the Common European Framework of Reference - is the scale almost every serious language course uses, and almost nobody explains. Here is what the six labels mean in practice, without the committee language.
The levels, in plain terms
A1 - you can survive an introduction. Say who you are and where you are from, ask and answer simple questions about immediate things, understand someone speaking slowly and clearly and being kind about it. Present tense, numbers, family, food, directions.
A2 - you can handle a routine day. Order, shop, describe your background and your job, talk about what you did yesterday and what you will do tomorrow. Past and future arrive here, which is the single biggest jump in usefulness on the whole scale.
B1 - you can hold a conversation. This is what most people mean by "conversational". You can deal with most situations that come up while travelling, describe experiences, explain a plan, give reasons for an opinion. You are still slow and you still hit walls, but the walls no longer end the conversation.
B2 - you can argue. Follow a fast conversation between native speakers, express a view with nuance, understand the main ideas of complex text. The gap between B1 and B2 is not more vocabulary so much as more precision: saying the thing you meant rather than the nearest thing you could reach.
C1 - you can be yourself. Use the language flexibly for social, academic and professional purposes. Choose between near-synonyms deliberately. Understand implicit meaning and register - when someone is being formal, dry, or rude.
(There is a C2 above that, which is usually described as native-like mastery. We stop at C1 deliberately: past that point what you need is not a curriculum, it is a life in the language.)
The two honest caveats
The levels are not equally sized. A1 to A2 is a short hop. B1 to B2 is a long one - by most estimates roughly as much work again as everything before it. The scale looks linear and is not, which is why so many learners feel like they have stalled at B1. They have not stalled; they have started the biggest band.
"How long" depends enormously on distance. A Spanish speaker learning Italian and an English speaker learning Korean are doing different amounts of work for the same certificate. Any hours-to-B1 figure that does not name the language pair is describing someone else's route.
Why a placement test should round down
Semantix places you with a short test - four questions at each level, A1 to C1 - and it is deliberately conservative: to be placed at a level you need three of its four right, plus at least half of everything below it. Get two of a level's four wrong and you are placed under it.
That sounds like the wrong trade until you look at the two failure modes. A strong learner placed one level low notices in about ten minutes, finds the content easy, and climbs out - the cost is a little boredom. A beginner placed at C1 is handed material they cannot engage with at all, and the rational response to that is to quit. The costs are not symmetric, so the test should not be either.
There is a second reason, and it is a lesson we learned the hard way on our own test. A multiple-choice placement test can be quietly guessable in two ways: if the correct answer clusters in the same position, and if a band can be cleared on a coin-flip because it only holds a couple of items. Both were true of ours until we measured it - simulated random answering placed a learner at C1 far more often than chance should allow. Both are fixed now, and both are checked automatically rather than reviewed by eye, because a test that renders perfectly and scores wrong looks exactly like one that works.
If you think your placement is off, you are not stuck with it. Placed too high? Step down on your profile at any time. Placed too low? Take the level challenge from your path - a short test at your level and the next one up - or simply work the path, and Semantix offers you the next level once you have earned it. What you cannot do is skip straight to C1 from a menu, because that is the same failure as a placement test that flatters you.
What each level looks like on Semantix
Every one of our 19 languages runs the full A1 to C1 span on all three of the things that set your ceiling - the curriculum path, the vocabulary decks and the placement test. That sounds obvious and is not: it is very common for an app to advertise a language and quietly stop authoring it at A2, so the "advanced" setting delivers beginner content with a harder label.
Concretely, across the 19: 342 units and 1,520 lessons, with 817 grammar notes that explain a rule in plain English before the drills that practise it, a checkpoint at the end of every unit that tests what you have kept, and 7,335 vocabulary cards banded by level.
Every language has a page per level - what that band covers, what it expects you to already have, and what you will be able to do at the end of it. Worth two minutes before you pick a starting point.