"They are wearing shoes with socks."
Translation:הם נועלים נעליים עם גרביים.
No, they are not optional. "נועלים נעליים עם גרביים" is a valid Hebrew sentence but it has a different meaning: it is a general statement about how people wear shoes. It means the same as "Shoes are worn with socks", except that it doesn't use the passive voice like I used in English.
In some cases it can be translated as an impersonal "they" (that doesn't refer to anyone specific), but that doesn't really work for the sentence above.
They speak English here = מדברים כאן אנגלית (General statement about people in the area)
They speak English = הם מדברים אנגלית (Statement about a specific group of people)