JASP comes with a handful of example data sets, which can be accessed from the ‘File tab’. Selecting these will load up the data, allowing you to inspect and analyse it.
JASP can also open data sets in the .csv (comma separated volume) data format. In practice, .csv files are often delimitered with a range of different characters and not just commas. When opening a .csv file, JASP examines the file, and automatically determines what the delimiters are. This usually means that JASP can open any .csv file without intervention from the user. The only absolute requirement, is that the .csv file contains a header row; where the names of each of the columns appear in the first row.
If you find a .csv file that JASP opens incorrectly, you can submit this to the JASP team, and they can look at improving the .csv handling heuristics. It would be worth checking if the .csv file is reasonable, and whether other software is able to open it correctly.
When opening a .csv file, JASP makes a “best guess” to assign variable types. More details below.