Salut: The word is french, but in english it is keep or hold (stay in slang usage)
En garde in French means "on (your) guard (because I am about to attack, in fencing)" in English.
"On guard!" in English is en garde! in French.
une garde
"garde-robe"
The word is garde-robe.
"Is he (issuing a) warning?" is a literal English equivalent of the French phrase Met-il en garde? The pronunciation of the present indicative in the third person masculine singular will be "mey-tee-law gard" in French.
"But take care, I'm telling you!" is an English equivalent of the French phrase Mais garde, dis donc! The statement translates literally as "But look out, I say therefore!" in English. The pronunciation will be "dee donk" in French.
en garde
The english word 'or' is spelled 'ou' in French.
It is usually pronounced as "ah-vant gard" in English. But French say it as "ah-vong gard".
Correct me if I am wrong, but I believe your are referring to the French phrase "En garde", which translates in English to "On your guard".
This is the same in French as it is in English.