English Translation
Wait here until I come back.
올 때까지 (ol ttaekkaji): This is a phrase made up of two parts. The first part is the verb 오다 (oda), which means “to come.” The verb stem is 올 (ol) because it is in its future tense form. The second part is 때까지 (ttaekkaji), which means “until” or “up to.” So the phrase as a whole means “until [I] come.”
기다려 (gidaryeo): This is the verb 기다리다 (gidarida), which means “to wait.” The verb stem is 기다려 (gidaryeo) because it is in its imperative form, which is used to give commands or requests.