English Translation
Lay down on the couch.
“Merebahkan diri” should be replaced with “Rebah” (i.e. drop the prefix and suffix as well as “diri/oneself”), and the English sentence should be “lie down”.
The root word “rebah” or “meredah” means “to lie down”. But the transitive verb “merebahkan” means “to lay something down”, “to knock someone down” or “to slaughter something (animals etc.)”. The suffix “-kan” is for a causative connotation in this case.