This is the 627th most frequent Indonesian word.
undang
"Undang" means "to invite" in English.
In this sentence, 'undang' is used in the verb form 'mengundang', which means 'to invite'.
Mereka mengundang kita ke acara pernikahan mereka.
They invited us to their wedding event.
Here, 'undang' is part of the compound word 'undang-undang', which means 'laws' or 'legislation'.
Undang-undang pemerintah tentang lingkungan harus diikuti.
The government's laws about the environment must be followed.
In this usage, 'undang' by itself refers to a 'law' or 'statute' in a formal context.