On the command line, enter:

cat /etc/os-release

NAME="Ubuntu"
VERSION="12.04.5 LTS, Precise Pangolin"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu precise (12.04.5 LTS)"
VERSION_ID="12.04"

To find out if it's 32 or 64-bit, enter the following:

uname -a

Linux ambit2-VirtualBox 3.2.0-126-generic #169-Ubuntu SMP Fri Mar 31 14:15:21 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux