Keep in mind that "weeds" are plants you do not want growing where you do not want them. So one persons "weed" may be anothers desireable plant. One example is "Goutweed", "Bishops Weed", "Snow in the Mountain", "Aegopodium podagraria" that some consider an invasive "weed" while others consider it an attractive ground cover. Some plants many consider "weeds", Dandelions, Plantain, etc., are grown by others as food crops. Sometimes asking 10 people whether this plant is a "weed" will often get you 15 different answers. If you don't want that plant growing where it is growing it is a "weed" and you can get rid of it. Is a self seeded Forget Me Not growing in a crack in the sidewalk a "weed" or not?

I assume this is Box Elder? Image link:

Your options in Ontario are much more limited then many in the United States have since many of the plant poisons readily available here have been banned for homeowner use there. Many of us do not consider any of the clovers to be "weeds" and do nothing to control them since they do help place nutrients in the soil and the flowers help feed the pollinators. The most common plant poison, 2,4, D with Dicanbra, has been banned in Ontario.

I tried to comment earlier but I didn't see it go through, so apologies if this winds up a duplicate. If it is Sage, it is not a variety I'm familiar with. The leaves are a little waxy and have zero fragrance. The plant has more of a tendency to spread out along the ground and creep: it first sends shoots straight up, but they lie down as soon as they reach a certain size (not even a very big size) , then lie flat and continue to grow along the ground. It seems to have a taproot. I took a photo of it next to my sage bush for comparison, it usually grows more flat like pictured. It could be Sage, I just wouldn't be familiar with what variety. Right now it's growing several feet out onto my sidewalk in mat form.