Northern Guangdong is in Guangdong Province in China. This region is less developed and industrialised than the coastal regions of Guangdong, with beautiful mountain hikes, rainforests and communities of ethnic minorities.
The region is split between Hakka speakers and Cantonese speakers. Hakka is the main language in Meizhou, Heyuan and Shaoguan, with accents and local expressions differing between the different cities; the Meizhou dialect is considered to be the prestige dialect. Cantonese is main language in Yunfu, Qingyuan and Zhaoqing albeit with distinctive accents and local expressions. Nevertheless, if you are fluent in standard Cantonese, this should not pose too much of a challenge, and most locals are also able to speak standard Cantonese.
The Yao ethnic minority speak their own languages, which are distantly related to Vietnamese and Khmer but unrelated to Chinese.
As with elsewhere in China, Mandarin is the official language, so most younger locals are able to speak Mandarin as well.
There are plentiful train, bus, and highway connections from Guangzhou and other cities of the Pearl River Delta.
Go hiking. This is a mountainous region with beautiful natural scenery. Shaoguan in particular is known for hiking.