。
Use acrylic-based paint.
Literal
Acrylic-type [attributive-の] paint [object-を] use-[polite command-なさい].
A short instructive line. ~なさい is the soft imperative attached to the verb stem — polite enough for a teacher or parent, more assertive than お~ください but less harsh than plain ~しろ. アクリル性 here functions like アクリル系 / アクリル製, marking a material category; the suffix 性 normally means 'property/nature' but loosely attaches to loanwords to form compound modifiers.