This is once as in something was done one time.

wa'logh romuluS HIq vItlhutlh
I drank Romulan ale one time.

vaghlogh chabHom Sop HoD
The captain ate a cookie five times.

Adding -logh to a number gives the notion of repetitions.

wa'logh once

cha'logh twice

Hutlogh nine times

These numbers function in the sentence as adverbials (see section 5.4 of the grammar guide).