You are running out of memory(RAM). You either need to increase the virtual memory size of your system or get more ram.
Reduce the lightmap size of the foliage assets in the scene, and consider reducing the amount of foliage until the issue is resolved. Either that, or increase the amount of RAM in your system.
If it’s a large world, look into building chunks of the level at a time using level streaming and world composition World Composition in Unreal Engine | Unreal Engine 5.1 Documentation