An interjection used to start speaking, get someone's attention, or show hesitation (like "um", "well", or "er").
あの、すみません。新宿駅はどちらですか？
Um, excuse me. Which way is Shinjuku Station?
あの…ちょっと相談があるんですが、今いいですか。
Well... I have something to ask — is now a good time?
あのー、次の電車は何時ですか？
Er... what time is the next train?