The particle O
O is a particle that is used with verbs. It comes after a noun and shows that it is 'the thing acted upon' by the verb. It is written with the hiragana symbol for wo (を). Sometimes in you will see people pronounce it as wo, but this pronunciation is becoming less common.
I will eat = watashi wa taberu (私は食べる)
In order to specify what you are eating in the above sentence you need to add the noun + O.
My girlfriend eats apples = ore no kanojo wa ringo o taberu
(I) drink beer = biiru o nomu (ビールを飲む)
(He) wont drink water = mizu o nomanai (水を飲まない)
The Japanese word for food is tabemono (食べ物). The word for drinks is nomimono (飲み物). Mono means thing, and you will see it used in many different words.
People eat food = hito wa tabemono o taberu (人は食べ物を食べる)
(She) will eat dinner = gohan o taberu (ご飯を食べる)
In Japanese the word gohan (ご飯) can be translated as either a meal or cooked rice. Rice is part of Japanese traditional meal, and it usually comes with almost every meal they eat. How it is translated depends on the situation, If someone asked what you ate for supper and you replied with gohan, it would mean rice.