CLB means Canadian Language Benchmark. It is the language framework Canada uses to describe your English level for immigration planning. That is why many people feel confused after getting an IELTS result: they have a band score, but Canada pathways often talk in CLB levels instead.
This page helps bridge that gap. If you already have IELTS General Training scores, use the calculator to estimate your CLB level. If you know the CLB level a Canada route needs, use the table to see the minimum IELTS score you should be aiming for in each skill.
The most important thing is that Canada decisions often depend on section scores, not only one overall IELTS band. A candidate can have an overall score that looks fine, but still miss the CLB level they need because one skill is too low.