I currently can't test this out since I only have the Houdini Apprentice Version, but I imagine you might have to look into exporting it as a VDB Volume. There might also be an issue with the material when exporting as it is a VEX Material and I don't know how Houdini might handle those materials. Hopefully this can point you in a better google searching direction.
how can I export this into UE engine? When I use an alembic export, it doesnt export anything.
I currently can't test this out since I only have the Houdini Apprentice Version, but I imagine you might have to look into exporting it as a VDB Volume. There might also be an issue with the material when exporting as it is a VEX Material and I don't know how Houdini might handle those materials.
Hopefully this can point you in a better google searching direction.