ryourinin ga tatemono no minamigawa de yasai o yaite iruno ga mieru.

I can see the chef grilling vegetables on the south side of the building.

Breakdown of ryourinin ga tatemono no minamigawa de yasai o yaite iruno ga mieru.

• を: direct object particle
• が: subject particle
• の: possessive case particle
• で: location particle

Questions & Answers about ryourinin ga tatemono no minamigawa de yasai o yaite iruno ga mieru.

Why are there two が particles in this sentence?

The first が (in 料理人が) marks the subject of the subordinate clause “料理人が … 焼いている.” The second が (in のが見える) marks the subject—or more precisely, the “thing that is visible”—for the main verb 見える. Grammatically, the entire nominalized clause “料理人が建物の南側で野菜を焼いているの” is what you “see,” so it takes が as the marker of what is visible.

What is the function of の after 焼いている?

Here, の is a nominalizer. It turns the verb phrase 焼いている (“is grilling”) into a noun phrase (“the act of grilling”). That allows the whole clause to be the subject of 見える:
料理人が建物の南側で野菜を焼いているの が見える
(“You can see the [act of the cook grilling vegetables on the south side of the building].”)

Why is 焼いている used instead of 焼く?

焼いている is the progressive form, showing that the action is ongoing—“is grilling.” If you used the plain form 焼く, it would simply state a habitual or general fact (“grills vegetables”) rather than what’s happening right now.

Why is で used with 南側 rather than に?

で marks the location where an action takes place. You grill で that spot. By contrast, に would mark a destination or point of arrival (e.g. 「南側に行く」 to go to the south side). So 南側で tells us “at/on the south side.”