of a kind or character

ऐसी

English Usage: Such behavior is unacceptable.

Hindi Usage: ऐसी व्यवहार अस्वीकृत है।

used to emphasize a particular quality

ऐसा

English Usage: I’ve never seen such beauty.

Hindi Usage: मैंने ऐसी सुंदरता नहीं देखी।