I would like to know the name of this red plant, please



Your plant is a red amaranth (Amaranthus), which is a large family that includes different species that we think of as weeds (such as pigweed), ornamental flowers (such as love-lies-bleeding), edible leaves (such as callaloo) and edible seeds, also called pseudo-grains for their nutritious content (amaranth).

You might be interested in this informative article from United Nations University:

Amaranth is native to Central and South America. In Toronto’s climate, it is grown as an annual, with seeds and starter plants available in spring.

I hope you find this information useful. Happy gardening.