A mountain bike is specially designed for traveling off-road and hill climbing. Using your mountain bike on the road is fine and is no issue at all. But make sure you do it safely and think about the following points: Focus on your shifting skills.
Mountain bikes are good for long rides in off-road areas; you can reach great distances without worrying about durability and function. However, if you're using mountain bikes on pavement, you may find yourself pedaling harder yet you are not going much faster.
Mountain bike tires wear faster on the road than road tires and do not get as good of traction especially wet. You can get hardpack tires that are more solid in the middle but they are not going to be good on mud and wet grass. Mountain on dry days with touring tires or hardpack is a better combo.
You can browse through our MTB bikes collection from the following link