IP (Internet Protocol) addresses are ways of identifying unique internet-accessible devices. They are also ‘addresses’ in the sense of showing its location (think of postal addresses).
When you type a web page into the computer, what you’re really asking is for some information from a different device (usually a big server somewhere in the world). There are several complex stages to finding this, but one of the key components is having an identifying ‘marker’ on each device; so you know which address to get the information from, and also so the information knows how to get back to you.
Recently, we’ve been running out of traditional (IPv4) IP addresses: using 4 different 32 bit numbers (eg. 18.104.22.168), giving us access to 4,294,967,296 possible unique addresses (232)).
IPv6 uses 2128 numbers, which is quite a bit bigger (340,282,366,920,938,463,463,374,607,431,768,211,456). An example of one of these is: 2001:db8:0:1234:0:567:8:1. To put that in perspective, 2128 E. coli bacteria (which are pretty small) would be around 26 times heavier than Earth (which is pretty big).
Take home point is we’re not going to be running out of IP Addresses soon.