I usually have an hour for lunch break. (Good sentence)

it usually starts at noon and ends at 1 o’clock in the afternoon.

-> It usually starts at noon and ends at 1 o’clock in the afternoon. (Start your sentence with capital I.)

by that time, I go to the company cafeteria with coworkers in my department.

-> By that time, I go to the company cafeteria with coworkers in my department. (Start your sentence with capital B.)

the company cafeteria serves 3 style menus for lunch.

-> The company cafeteria serves 3 style menus for lunch. (Start your sentence with capital T.)

the 3 style menus is consists of the korean, western and chinese food. so, I can choice one menu among the 3 style menus.

-> The 3 style menus is consist of the Korean, Western and Chinese food so I can choose one menu among the 3 style menus. (Start with capital T and use CHOOSE since it's a verb.)

I tend to prefer Korean food. because I think the korean food is lighter on my stomach than the western or chinese food.

-> I tend to prefer Korean food because I think the Korean food is lighter on my stomach than the Western or Chinese food. (Use capital letters for proper nouns and remove THE.)

After eating, I stop by the park to enjoy walking with my closest coworker and I.

-> After eating, I stop by the park to enjoy walking with my closest coworker. and I. (You can remove "and I" since you already used I as your subject.)

we like to talk about our company because it is something we have in common.

-> We like to talk about our company because it is something we have in common. (Start your sentence with capital W.)