See is an irregular lexical verb. It has the third person form "sees" (/si:z/), with the -ing form "seeing" (/si:jɪŋ(g)/). It has the irregular preterite "saw" (/sɔ:/) and the irregular past participle "seen".
See can be used to introduce a relative clause, e.g. "I see that you've not done your homework again".
Saw is a homograph and homophone with another irregular verb, saw.