If you say the first five letters of a particular seven-letter word out loud, you pronounce a vegetable (but only one).
If you say the last five letters of the same seven-letter word, you pronounce the same vegetable (but more than one).

What is the seven-letter word?

When you say the letters out loud are you pronouncing only the word that is the vegetable or are you pronouncing a phrase?

You say a phrase and then you say vegetables.

peaceful - pea peace (peas) flu

OOppss disregard - this is an 8 letter word you wanted 7.

Appease - a(p)pea + peas(e)

Lex got it!