When talking with my boyfriend and friends they use the word "Bakale/Bakalle" very often as something similar to "bak" perhaps, I really don´t know but that´s the understanding I have. Could anyone tell me what it means?

My guess is maybe they are saying bakalım

This means let´s see!

It comes from the verb ´bakmak´ (to see, to look), with the suffix alım added, which means let us or let´s.

Or maybe bakkal , which means grocery store.

Most probably it is "bak hele" which has the same meaning as "bak sen"

 never heard about "bak sen" but i heard about "baksana"

bak hele! : hey! (expressing that you gonna say something)

bak hele, bu akşam gelecek misin? (hey, are you gonna come tonigh?)

bak sen! : oh really ? (surprising and sometimes belittling interjection).

Can sınavı kazanmış! (Can succedded the exam!)

Bak sen! (Oh, very good!)

thx

I understand very well now.

Thanks for the explanations Henry, Toggle, Zeytinne and Turkishcobra

 "Bak hale" and "bak sen" can also express an astonishment.