5 card majors is the main system used by bridge players in the USA, Canada and much of the rest of the world. (One of the main alternatives is Acol bridge, the system played in the UK, Ireland and New Zealand.)
The basic premise of 5 card major bridge bidding is that the opening bidder makes an opening bid in a major suit if they hold 5 or more cards in the suit. If the opening bidder doesn’t hold a 5 card major suit, then they open with a minor suit bid. This is one of the differences between the 5 card major bidding system and Acol.
The hand contains 13 high card points, so you have enough points to open the bidding.
In Acol bridge you would open this hand with a bid of 1 Heart.
In 5 card majors you would open with a bid of 1 Diamond as you do not hold 5 cards in either of the major suits.