"To his left" means "on the left side of him" in Engpsh. This phrase is a prepositional phrase that is used to describe the location of something relative to something else. The preposition "to" indicates direction, and "left" is a noun that refers to the direction that is opposite to the right.
Here are some examples of this phrase in a sentence:
He stood to the left of the stage. (他站在舞台的左边。)
The bank is located to the left of the post office. (邮局的左边有一家银行。)
She sat to her husband's left at the dinner table. (她在晚餐桌旁边坐在丈夫的左边。)