These are buttons. They get bigger as they go from left to right.
Buttons are nice because they can take you to other websites, activate certain things, or just do cool stuff in general.
Buttons enhance the user experience and make sites easier to use. They guide the user on where to go. Buttons can be visually appealing, and the design and placement can make the aesthetics of a website much better.
With creative and thoughtful design, buttons can make a website far nicer and more appealing for the average user to visit on a regular basis. The better the site, the more customers, the more customers, the better the site, etc.