Qasd Al-Qurbah means that the act must be done with the intention of seeking closeness to Allah swt. For example, salah, hajj, sawm, wudu and ghusl etc. All these acts are not valid without the specific intention of doing them for the sake of Allah.
There are some other actions where you wouldn’t need this intention. For example, making something tahir (purified). It wouldn’t be necessary if someone was removing an impure substance to utter this intention.
May Allah grant you success