* In many Western cultures, putting two fingers up facing you is considered an offensive gesture, similar to flipping someone off. This is because it resembles the middle finger, which is a vulgar symbol.
* In some other cultures, the same gesture can have a different meaning. For example, in parts of the UK, two fingers up can be a friendly gesture, similar to giving a thumbs up.
It's always best to err on the side of caution and avoid using this gesture if you're unsure of the context.
If you want to express a friendly gesture, there are plenty of alternatives that are universally understood, like a thumbs up or a wave.