GIS stands for Geographic Information Systems. These are information systems (software) used to manage geographic data.
Geographic data (or geodata) are data describing the location, position or spread of things, usually using coordinates. Combined with descriptive data these coordinates can be imported into a GIS where you can store, process and visualize the information.
Uppsala University Library offers introductory courses in a GIS called QGIS. It is an open source software that is free to download and use.
For upcoming courses, please see below.