How does this pattern work?
(KB.1,wf, )twice,(wf.,sl1,k1,psso,wf,)twice,
how do you wf twice?

The ‘w.f.’ is the same as ‘yf’ or just YO. You would be doing everything inside the () twice, not just the yo. So KB1, yo, KB1, yo, and yo skp yo twice. If that’s all there is to the row, you would be doing a double yo, 2 of them together - just wrap the yarn around the needle twice on the YO. Can you link us to the pattern, or write out the complete row and post it?