Bagi literally means ( to Give ) ... but it can also be used for other purposes ... i'll try to give examples for each use of BAGI ... hoping that i can help u a bit
1- BAGI can be used as ( to give )
ex : BAGI saya alamat anda
which means .. Give me your address
2- BAGI can be used as (as for me/in my opinion)
ex : ramai orang cakap buah durian rasa sedap, BAGI saya rasanya tidak sedap
which means .. many people say durian tastes good, in my opinion(as for me) it is not tasty
and i guess saying ( Bagi Saya ) is much easier than saying ( dalam pendapat saya) which also means in my opinion
3- BAGI can be used as ( to/ for the purpose of )
Ex : Kita mesti jaga pendidikan, BAGI menghasilkan insan yang lebih berintegriti
which means ..... We must take care of education, TO get a more integrated human
or it means ........ We must take care of education, for the purpose of getting a more integrated human
and just as Aiz said ... Bagi tahu = tell/ inform
hope i helped u a bit :)