With Google's mobile-first indexing, a website's mobile version is now the starting point for what Google includes in their index, making it the baseline for how they determine rankings. A mobile-friendly design is, therefore, not just a convenience for users but a critical factor in SEO performance.
To ensure your website is mobile-friendly, it should feature a responsive design, meaning it automatically adjusts to fit the screen of any device. You can check your website's mobile-friendliness using tools like Google's Mobile-Friendly Test. Enhancing mobile usability may include increasing font sizes, ensuring easy navigation, and making buttons large enough to tap with a finger.