芒草定係六位呀
There are six of them.

Cantonese Sentence Breakdown

芒草 mong5 cou2
lemongrass
定係 ding6 hai6
(conjunction) or
六 luk6
six
位 wai6
position
location
place
seat
classifier for people (honorific)
classifier for binary bits (e.g. 十六位 16-bit or 2 bytes)
throne
post
rank
status
呀 haa1
(particle equivalent to 啊 after a vowel, expressing surprise or doubt)