Openings tab here is a measure of how frequently an opening is played. For example, the moves you see on top are the most common ones, followed by lesser common ones. The percentage bar dictates how many matches that were recorded ended in whose favor … the leftmost being the percentage of games won by white, then the games drawn are the middle percentage and then the rightmost is percentage won by black. However, as a beginner it's best not to worry about these things. Just select an opening from the list, I suggest to see the four knights, Italian or Spanish and work around them!
Cheers!!
Thank you :)