A more thorough explanation:

The Washington D.C. Voting Rights Amendment was a proposal made by Congress in 1978 to the U.S. Constitution. Its aim was to give Washington D.C. similar representation to states in the national government.

Currently, Washington D.C. has limited representation in the national government, despite having a greater population than Wyoming and Vermont. The 23rd amendment to the Constitution grants D.C. one representative in Congress who can only draft legislation, not vote. Additionally, citizens of D.C. can only have as much representation in a Presidential election as the least populous state.

The D.C. Voting Rights Amendment would have repealed the 23rd amendment and given D.C. much of the same representation as a state. D.C. would have had two senators and the same amount of representatives as a state of the same population. Furthermore, D.C. would have had the same ability to vote in the electoral college as a state with the same population.

For example, if the D.C. Voting Rights Amendment had been ratified, D.C. would have had two senators and the same number of representatives as a state like Wyoming, which has a similar population. This would have given D.C. more say in national politics and a greater ability to advocate for its citizens.

It is important to note that the amendment would not have made D.C. a state, as has been proposed in recent years. The amendment was only ratified by 16 states, falling short of the 38 required to ratify before the amendment failed in 1985.