Canada's Express Entry system uses language test results converted to Canadian Language Benchmark (CLB) levels. The accepted tests include IELTS General Training and PTE Core, and each converts to CLB in its own way.
These articles explain CLB levels, how test scores convert, how long results stay valid, retakes and how to choose and prepare for the right test for your application.
CLB 7 in IELTS General Training means 6.0 in every skill, not overall. What IRCC asks for, the rules that catch applicants out, a plan for your weakest skill.
Aiming for CLB 7 in Express Entry? Here is the exact PTE Core score range for listening, reading, speaking and writing, with the official source linked.