The sentence you wrote is almost correct but needs a little adjustment for grammar and capitalization.
Here is your original sentence:
baby hares wait for their mum, snug under a bush.
Corrections needed:
- Capitalization: The first word of a sentence should start with a capital letter, so baby should be Baby.
- Punctuation: The comma is fine here to show that the phrase 'snug under a bush' describes where the baby hares are waiting.
So the corrected sentence is:
Baby hares wait for their mum, snug under a bush.
This sentence means that the baby hares are sitting comfortably and safely under a bush as they wait for their mother.