Dividend units are like little treats that a company gives to its owners (shareholders). Imagine you have a cookie, and your friends helped you make it. You might want to give them pieces of the cookie as a thank you for their help. This is kind of like what a company does when it gives out dividend units.
When a company makes a profit, it decides how much of that profit it wants to keep (to reinvest in the company) and how much it wants to share (give out to their shareholders). This shared portion is called the dividend.
Dividend units are a way of measuring how much of the company's profits go to each shareholder. If the dividend is $1 per share, and you have 10 shares, you'll get 10 dividend units (or "pieces of the cookie") worth $1 each.
Some companies pay out their dividends every year, while others pay them out quarterly (four times a year). It's like getting a little bonus for being a part-owner of the company!