The three
kira-kira ‘roughly’, from kira ‘to guess’
sekitar ‘around’
lebih kurang ‘more or less’, literally ‘more less’
Kira-kira lima menit. ‘About five minutes.’
Sekitar jam tujuh. ‘Around seven.’
Lebih kurang sepuluh orang. ‘Ten people give or take.’
All three are interchangeable in most sentences. Kira-kira is the most conversational.
As a question opener
Kira-kira placed at the front of a question softens it into a request for an estimate rather than a demand for a fact.
Kira-kira berapa lama? ‘Roughly how long will it take?’
Kira-kira bisa nggak? ‘Do you think it might be possible?’
This is a useful habit. Asking for an exact figure puts the other person on the spot; asking for an estimate does not.
Sekitar for places too
sekitar sini ‘around here’
di sekitar pasar ‘in the market area’
Same word, doing geography instead of arithmetic.
The cultural note
Precision is not the default here in the way it is in northern Europe. A time given as jam tujuh often means somewhere in that region, and lima menit for a distance means it is not far.
This is not carelessness. It is a system where being slightly loose leaves room for circumstances, which in a country of traffic, weather and family obligations is a reasonable design.
Where precision genuinely matters, say so:
Jam tujuh tepat. ‘Seven o’clock sharp.’
Pas jam tujuh. Same, casual.
What you’ll actually hear
What the book says: Perjalanan memakan waktu kurang lebih dua jam.
What you’ll hear: Kira-kira dua jam-an.
That -an suffix on a number is a casual way of saying “about”, and it is everywhere in speech.