These appear to be arborvitaes although the photo is so dark it’s hard to be completely sure. These also look like plants that were recently put into the ground, yes? There can be several reasons plants get brown and die, and from a photo alone it’s impossible to tell which reason has caused your plants to do this, but here are a few things that come to mind immediately:
1. These look like they were planted above ground level. It almost looks like a small berm was raised in order to give these plants a few more inches in height from the get-go, and this actually makes the plants roots dry out faster. The most common cause of a plant browning like this is too little water during the first and second year after planting, and raising up a mound to plant in or on doesn’t help.
2. If these plants weren’t watered deeply (using a soaker hose or sprinkler once a week for about two hours) the cause was probably drying out. Hand watering is never enough, especially when the ground slopes away from the plants as it appears to here. Automatic sprinkler systems that only come on for 15 or 20 minutes are also not enough as they only water the top three inches of the soil.
3. Was the burlap removed completely from the root balls if these were balled-and-burlaped plants? Burlap left on the rootball contribute to root-drying and early death of plants. Always take all burlap, rope, and wire cages off.
4. Fertilizer burn can also look like a plant has dried out. If the plants were given a synthetic fertilizer at too high a concentration, that would contribute to the death of plants.
There are so many plants here and they are so close together that even if you removed the dead ones, and pruned out dry branches from the others, the remaining plants might make it and become a good screen. But you’ll need to add more soil so that they aren’t on such a narrow ridge, mulch with some composted manure topped by bark mulch to hold water in the soil, and water them deeply once a week if it doesn’t rain. Deep soaking less often is always better than a little every day.