WGS_84 per se isn't a coordinate system, it is a datum, which is why you can have
GCS_WGS_84 a geographic coordinate system with that datum, its coordinates are in decimal degrees
UTM zone 44N WGS 84 a projected coordinate with that datum, but its units are in meters and the projection is a universal transverse mercator projection, it is in zone 44 in the Northern hemisphere.
Don't get the little bits around the datum description.
If you find a file that doesn't have a "defined" coordinate system. Don't use it
Do not under any circumstance use the Define Projection tool for anything else other than fixing the above, although you shouldn't use it unless you really know that it is in that coordinate system.
Use the Project tool to "make" a new file with a new coordinate system.
Also.... the first layer added to a map, defines its coordinate system, so add things properly.
Avoid any basemaps that use Web Mercator (the story is too long) especially if you intend to do any analysis.
Your questions are still being virus scanned, ..... but I couldn't wait 😉
... sort of retired...