"Several kilos" means a few or more kilograms, which is a unit of weight. It refers to an amount that weighs several times more than a single kilogram. Full definition
I live in a warm climate, so of course my Havanese loves it, and every evening she brings home several kilos of sand from the beach and leaves it scattered over my bedroom floor. (pethelpful.com)
Even the wiring can be stripped of unused cables, saving several kilos. (evo.co.uk)
But in general, mothers can safely lose several kilos per month — maybe five pounds per month, safely at that trajectory, without affecting the nutrition she delivered to the baby. (phillyvoice.com)