You can take a Cantonese course online on Learn Chineseez website. Additionally, you can also learn this course on Cantonese, euroasia, and Omniglot website.
It works the same as speaking any language. If you known Cantonese, you can speak it. You also take classes to learn it.
Cantonese people mainly speak Cantonese, a Chinese dialect. Additionally, many Cantonese people may also speak Mandarin, which is the official language of China, as well as English, due to Hong Kong's history as a British colony.
Here are some examples of Cantonese.
'Cat' in Cantonese is 'Maau.'
In Cantonese, "king" is pronounced as "王" (wong4).
'Flower' in Cantonese is 'Faa.'
'Basketball' in Cantonese is 'Laam Kau.'
si do be lei, is strawberry in cantonese :)
Cantonese speakers may be able to understand some Mandarin Chinese due to similarities in vocabulary and grammar, but the two languages are distinct. Differences in pronunciation and tones can make it challenging for Cantonese speakers to fully understand Mandarin, and vice versa.
TVB is a Cantonese channel, but occasionally will broadcast Cantonese dubbed Mandarin drama shows.
Of you are cantonese, it is easier to learn but just speak it to the people you know that know cantonese or if your parents are cantonese, speak to them. There are also some lessons that might be available.