This is a very common term in astrology, but many people are not aware of it. The Lord is also known as Ruler and Swami in Vedic astrology. The term is used in connection with houses. There are 12 divisions in astrology, they are known as houses. When you take your birth chart, you can see a few columns or boxes, and they are known as houses. Each house is ruled by each sign/Rasi. Each Rasi is ruled by a planet, and that planet is known as the lord of that house. Each House gives us information about the various features of our life. Like Marriage, wealth, health, career, and much more.
There are 12 rasis and here are the lords of that Rasi.
According to each lagan/Ascendant or rising sign the rulers will change.
if you are Aries lagna/ascendant your first house will be ruled by Mars, 2 – Venus, 3. Mercury
If you are a Taurus lagna/ascendant your first house is ruled by Venus, 2-Mercury, 4-Moon
It can be complex in the beginning to identify the lords, but as you learn more about astrology, you will come to know them easily.