。
I'm the patient type.
Literal
I [topic-は] patient temperament.
我慢強い (がまんづよい, 'patient, persevering') — 我慢 ('endurance') + 強い ('strong'). たち ('temperament, disposition') describes one's innate nature — ~たちだ means 'I'm the type who is X.' A concise self-description using a culturally valued trait.