"On guard!" in English is en garde! in French.
"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.
en garde
"On guard! Touched!" is a literal English equivalent of the French phrase En garde! Touché! The phrases most famously reference a fencing scenario in which one fencer warns the other to beware and then realizes physical contact through a fencing move. The pronunciation will be "aw gard too-shey" in French.
En ré mineur in French means "in D minor" in English.
Travaillez en paires in French means "Work in pairs!" in English.
Comment dit-on en français? in French is "How does one say in French?" in English.
Un film en anglais in French means "a film in English" in English.
Que veut dire en français? in French is "What does (it) mean?" in English.
Mais parle-moi en français! in French means "But speak to me in French!" in English.
'what is 'friends' in French'
"Pouvez-vous parler en français" translates to "Can you speak in French?" in English.