"Balik" is the first command, meaning "turn back", "turn around", or "reverse".
"Lalu" means "then".
"Naik" is the second command, which can have multiple meanings depending on the context but loosely means "up". So "go up", "ascend", "climb", "increase", etc. Like how in English we could say "go up the lift", "go up the road", "go up the stairs", "turn the music up", etc.
Hey @RobertEddy, I was very confused myself until my own teacher explained that some words translate differently. My favorite word in Indonesian, "ngapain", means "What are you doing?" That said, the translation for this question is incorrect. "Naik" is a verb that means "to ride". In the Indonesian culture, this word is used with atas or "up" to state "going up the stairs". (Naik atas.)
Naik actually has several meanings. Ride is one, go up is another, climb is another. 'naik ke atas' actually means 'go up to the top' and yes, you would use this for going up stairs or escalators or elevators. KBBI (kamus besar bahasa indonesia) actually lists 8 meanings for the word naik.
This is pretty common in Indonesian. I think English in general most words have a single meaning, but there are several words that have a similar meaning. Indonesian, on the other hand, has fewer words with similar meanings overall, but many words have several meanings depending on context.