A lot. Beyond simple links, you can add a featured/highlighted link, headings, text blocks, dividers, custom HTML, images, a phone call button, a digital business card (vCard), a PayPal payment button, WhatsApp call or message buttons, and uploaded video, audio, or PDF files.
You can also embed content from YouTube, Spotify, Apple Music, SoundCloud, TikTok, and OpenSea, add social profile icons (around 40 platforms supported), embed a Google Map, add an Eventbrite or Calendly booking widget, a countdown timer, an RSS feed, a newsletter signup form, a contact form, a product for sale, and a live chat widget.