It can be a mess, but Lightroom has an Aperture Importer plugin that can help. I'd recommend you first use a small subset of your main Aperture library, and import into a test Lr catalog.
It also helps to do some prep in Aperture first, and understand the differences. For example, it makes a BIG difference if you manage your photos in Aperture (i.e. copy them INTO an Aperture library) or reference photos in Aperture (they remain outside of the Aperture library in regular Finder folders in say your Pictures folder).
Also, while many things carry over, photo adjustments (like say a bunch of color changes, dodging, etc) in Aperture do NOT. There are several ways to deal with that, but we'd need to know more. In general you have to export those adjusted versions from Aperture.
If you do have a lot of adjusted images you want to save, I'd also look at Aperture Exporter (note it runs FROM Aperture, and is an external application). It offers some features the IMporter doesn't. https://apertureexporter.com/ They have a demo available.