What is the meaning of ба?

alternative form of бе (be)

and

well, too (reinforces disagreement, opposition of the speaker at the preceding words of the co-locutor)

even (emphasizes width of permittance of something)

yuck (expression of disgust)

why!, well I never!, wow! (an exclamation of surprise, especially at an unexpected meeting)

granny, gran

at

to

in

for

Source: wiktionary.org