j’achète (I buy)

tu achètes (you buy)

il achète (he, she it buys)

elle achète

nous achetons (We buy)

vous achetez (You buy)

ils achètent (they buy)

If you use the imperative form (that means you don’t use the subject and make it a command…) you could simply

say

“Achetons!” which would mean “Let’s buy” or perhaps more appropriately translated “Let’s go shopping”

(You could also say “allons acheter” which is literally “lets go to shop”, but the “nous” or “we” form sounds moure like Ashton. The only difference is the way french sort of swallows the ‘on” ending rather than sounding it out.

A little context would help. Are you sure it wasn’t German, “achtung,” which means “careful”?