The Iwatobi Swim Club needs one more member before it can participate in relays.  Nagisa has set his sights on his classmate Rei, who is a member of the track team.  Despite Rei's refusal to join, but Nagisa appears intent on recruiting Rei into the swim club.
Ah, I see.
Ah, verstehe.
Ya veo.
Claro.
Je vois !
Ah, capisco.
Ah, entendo.
Ясненько.