The disk space total would actually add up to 160Gb especially if there's a recovery partition on the disk as well.
Real disk space is always less than the preferred sizes they use which can be a little confusing.
But it seems to be in two partitions and I'm really not sure why Acer would divide the disk up like that.
It won't do any harm, you could use one partition for storage, but if you'd rather resize the partitions or just have one big hard drive, you'll have to get hold of some partitioning software. I think there are some freebies available but not sure.
And welcome to the forum btw