This is not actually slang, but standard Spanish. 'Te veo' translates to 'I see you' in English. It's often used when someone wants to say 'I'll see you' or 'see you later'. In some Latin American countries, it's used as a casual way to say goodbye.
Examples
- Spanish: Nos vemos mañana en el cine, te veo.
- English: See you tomorrow at the cinema, I'll see you.