Téigh isteach sa scoil agus fan ormsa ag an oifig.
Go -- into -- in the -- school -- and -- wait -- for me -- at the office
isteach - - into (adverb of motion)
sa -- in the - - originally ins an
i.e the preposition i - - in with the definite article an - - the
Téigh - - go and fan - - wait are verbs in the
imperative mood, an modh orduitheach.

ormsa - - emphatic form of orm - - on/for me

ag an oifig - - at the office