"You visit our mother."
Translation:Matrem nostram visitatis.
the adjective is noster (male), nostra (female), nostrum (neuter) at the nominative. At the accusative singular, nostrum is both for male and neuter, while nostram is for female. In this case, the mother is female, so we use nostram. Here's an extra help: https://en.wiktionary.org/wiki/noster
In the Latin present indicative the second person plural (you) gets a termination -tis. Because visito is a first conjugation verb, its thematic vowel is -a, so it becomes visit - a - tis.