The phrase "zài nǎr 在哪儿" and "zài shénme dìfang 在什么地方" both can be used to ask the location of someone/ something.
This sentence indicates the sequence of two actions - going to the canteen first, and then the stadium. When planning activities or routes, or deciding where to go or what to do first, you can use "xiān 先" (first) and "zài 再"(then), as shown below:
Monosyllabic words, as illustrated above, are typically not used in isolation but are often modified by other nouns. For instance, "xuéxiào lǐ 学校里" (in school), "xuéxiào ménwài 学校门外" (outside the school gate), "jiān (shāzuǐ) dōng 尖(沙咀)东" (TST East), and so forth.
Additionally, these monosyllabic words can function as modifiers for other nouns, as exemplified by constructions like "qiánmén 前门" (front gate), "hòumén 后门" (back door), "nánlóu 南楼" (south building), and "běilóu 北楼" (north building).
Usually, people in the Mainland use "dōng 东" (east), "nán 南" (south), "xī 西" (west), and "běi 北" (north), to describe directions, while people in Hong Kong prefer to using "qián 前" (front), "hòu 后" (back), "zuǒ 左" (left), and "yòu 右" (right). Therefore, in Mandarin, "东", "南", "西", and "北" are more often used, while in Cantonese, "前", "后", "左", and "右" are more common.