As follows:

milk tea originates from British colonial rule over Hong Kong. The British practice of afternoon tea, where black tea is served with milk and sugar, grew popular in Hong Kong. ?

Milk tea is similar, except with evaporated or condensed milk instead of ordinary milk. It is called "milk tea" to distinguish it from "Chinese tea" which is served plain.

Translation:

Milk tea originated from the British colonial rule of Hong Kong. The British habit of drinking afternoon tea, which is black tea with milk and sugar, is becoming increasingly popular in Hong Kong.

Milk tea is similar, except that condensed milk or evaporated milk is used instead of ordinary milk. It is called "milk tea" to distinguish it from "Chinese tea", which is plain tea.