It was “just a letter” written on behalf of the British state giving their full support for the creation of Israel in what was, at the time, British-occupied Ottoman land that the British had already promised to return to the Palestinian people.
So yes, the British literally give the land - which was not theirs in any legitimate form - to a group other than the native population.
They then provided (and continue to provide) financial, political and military support for decades, while Palestine was progressively colonised.