When you get angry, count to ten.

Literal

Belly [subject-が] angry-stand [when-とき] [topic-は], ten [until-まで] count.

A piece of anger management advice. 腹が立つ is the intransitive version of 腹を立てる — 'anger rises.' 十まで数えなさい uses まで (until) and なさい (mild command).