Nintendo is always experimenting with ideas and patents are a very important part of this process. Sometimes it will file something to do with hardware and other times it's more focused on gameplay experiences.
On this occasion, it's about the gameplay side of things - with the latest filing apparently focused on improving mini-maps. The gist of it according to Axios' Stephen Totilo is that it's about making "better mini-maps" for series like Splatoon.
You can see the original patent filing here (it's a huge wall of text). There are various references to "shooting ink" and "painting" areas with ink, throughout the patent - which means it could potentially be something to do with the upcoming Switch release Splatoon 3. GoNintendo has also provided a brief summary:
"this mini-map approach aims to make it easier for players to understand not just their own position, but the position of helpful items and other areas of import on the map. The cameras used will shift dynamically based on moment-to-moment action, as well as with the changing areas of importance on the map."
As with all patents, there's no saying Nintendo will actually take things any further. So, we'll just have to see what comes of it.
This filing follows some controller patent news in March, dating back to a patent last year: