The setting in Omar Sakr's poem "Botany Bay" is the "grassy plain" which overlooks the eponymous bay. Botany Bay is close to Sydney, on the south-east coast of Australia, and it is famous as the place where James Cook and the HMS Endeavour first landed in 1770.
In the poem, there are children playing on the "grassy plain," and we can infer that it is very hot because the children are "squinting / in the heat." We are also told that where the "grassy plain" meets the water it becomes "pebbled cliffs and sand." Across the plain there wafts the smell of "fish and chips steam[ing] in the sun." Overall the setting is described as a peaceful, beautiful, rather idyllic place.
There is a bridge from the "grassy plain" to "Captain Cook's museum," and the museum "looks both close / and awful in the distance." It is this aspect of the setting (the museum) which prompts the speaker to consider Australian identity. The museum has been erected to mark the arrival of Captain James Cook and the speaker refers to this arrival as "the invasion." The choice of this word immediately suggests that Australia, at least from the speaker's point of view, has forged for itself a proud identity, independent of the British colonization which followed James Cook's "invasion."
As the speaker imagines what James Cook might have thought about Botany Bay today, he envisions the bay, and thus, by extension, Australian identity, as multicultural, independent and free. The multicultural aspect of the setting is implied by references to the different types of food ("fish and chips … pide, eggs, / cucumber and focaccia") being enjoyed by the people on the plain, and also by the adjective "hijabbed" used to describe the sky. The freedom that the speaker associates with the bay is implied by that fact that he is lying idly on the grass, looking up at the sky, and it is implied also by the aforementioned children who are playing freely on the plain.