Tiens-toi bien means 'sit straight!' (or 'stand straight') in English. In the figurative sense, that could mean 'behave yourself well'
Je tiens a toi
jusque, jusqu'à are the French spelling for until. Until then, be quiet: jusque là , tiens toi tranquille.
"tiens c'est pour toi ça la belle mère" translates "here's this for you the mother-in-law"
'Keep quiet' is translated 'tiens-toi tranquille' in French.
je tiens toujours tant à toi
"jusque là " jusque là , tiens toi tranquille : until then, stand quiet.
The most beautiful person I know it 's you my love
Évite les ennuis - tiens toi à l'écart des ennuis / des problèmes
The verb "Tenir" means "To hold". "Tiens" is the informal second-person personal pronoun version of this verb. Therefore "Tu tiens" means "You hold" or "you are holding".
It means : It is
tiens-toi droit is the French equivalent of 'sit up'. The sports exercise 'sit-ups' is called 'les abdos' (after the belly muscles 'abdominaux')