How to get the size of a folder in SSH

du -sh folder1

You can additionally get the amount of disk space left on a device by using the following

df
df -H

Sample Output

Filesystem           Size  Used Avail Use% Mounted on
/dev/mapper/cl-root   29G   17G   13G  58% /
devtmpfs             1.5G     0  1.5G   0% /dev
tmpfs                1.5G     0  1.5G   0% /dev/shm
tmpfs                1.5G  153M  1.4G  11% /run
tmpfs                1.5G     0  1.5G   0% /sys/fs/cgroup
/dev/sda1            1.1G  399M  665M  38% /boot
tmpfs                297M     0  297M   0% /run/user/0
sudo du -h --max-depth=1 autobulbs/
28K	autobulbs/.well-known
1.6M	autobulbs/admin
2.9G	autobulbs/backup
13G	autobulbs/