What does L2, B2, B3, etc mean?

[EdmontonLaw]

I tried to Google it but cant find anything. I see people using these terms when they talk about their GPA

[GoatDuck]

L2 — last two years’ GPA

B2 — best two years 

L3 — last three years 

B3 — best three years 

[EdmontonLaw]

This makes a lot of sense thanks