YMCA is made from the first letters of Young Men's Christian Association, and you say the four letters one by one. As the name of the organization it takes the: the YMCA runs classes, she works for the YMCA. The organization owns and runs buildings in many countries, and what it offers is mostly somewhere cheap to sleep and somewhere to do sport, aimed at young people. The name is old and says Young Men's, but the places it runs are described in the source as being for young men and women. In the United States and Canada people often shorten it in speech to the Y.

Here the letters name a building rather than the organization, so the word becomes countable: a YMCA, two YMCAs, the YMCA near the station. Inside there is usually a pool or a gym, and often rooms where people can stay for a low price. You meet it with the ordinary place words: stay at a YMCA, swim at the YMCA, a new YMCA opened. The source describes these places as being for young men and women, even though the organization's name says Young Men's. In the United States and Canada the building is often just called the Y.