Yumcha (饮茶) literally means "drink tea", it is an act of drinking chinese tea.
Nowadays Malaysians use the word to mean "hang out" or to have a high tea supper of sorts. It is a significant Malaysian culture and I reassure most Malaysians used the phrase "jom yumcha", which means "let's go have a drink".
The session could last as short as half an hour or blowing water from sunset to sunrise. But the most important things are the shameless chit chats between friends which further solidify the friendships, and the deep talks those can cure the broken heart.
Love life, love yumcha.