HDMI is a way to connect your monitor or TV to your computer. HDMI stands for High-Definition Multimedia Interface.
SVGA which has been used a long time used the blue connector on your computer and was only for analog video and did not include audio which had to use a separate connection.
HDMI is digital video and sound combined and is a high quality using digital signal. It was developed by a number of companies and became available in 2003.
Computer monitors and TVs now sold all contain HDMI interfaces. Computers including desktops, Laptops and tablets normally all have HDMI. Some may just have either HDMI or SVGA or may have both. There are adapters available from HDMI to SVGA.