'It's giving' is a 2021-onward expression meaning 'it has the vibe of' or 'it reminds me of'. 'It's giving 90s' = 'it has a 90s feel'. 'It's giving rich aunt energy' = 'it has the vibe of a rich aunt'. Used to compliment, mock or describe aesthetics. If your teen says 'it's giving', they are characterising the vibe of something. Harmless and very common in current youth speech. Originated in ballroom and drag culture.