Every stock has a date where they pay a dividend. Most stock brokers like webull will have there a tab called the declaration where the company has the last day you can buy the stock so you can get the next dividend.
The ex-div date is the date when you get the dividend. But you can also look up the dividend date on sties like https://seekingalpha.com/ and https://www.dividend.com/ where they will have the dividend payment on their site. I made a video below going over more details