We had these bushes for a few years now and this year after the harsh winter the leaves have turned brown. What can we do?
Our Holly Berry Leaves Turned Brown Over Winter
You're not alone. Holly was probably the most seriously affected plant this past winter. This article will tell you about "winter burn:" https://www.gardeningknowhow.com/plant-problems/environmental/winter-burn-in-evergreens.htm
If you're not sure about pruning your holly, this article should help: https://www.gardeningknowhow.com/ornamental/shrubs/holly/trimming-holly-bushes-how-to-prune-holly-bushes.htm