Brahms showed great talent for music at a young age. He composed his first piece at the age of ten. He also began performing in public as a pianist. After graduating from high school, Brahms moved to Vienna to study music. He studied with the composer Simon Sechter.
In Vienna, Brahms began composing seriously. He wrote a number of works, including his first symphony, which he premiered in 1876. Brahms also became a conductor. He conducted the Vienna Philharmonic Orchestra for several years.
In addition to his work as a composer and conductor, Brahms was also a talented pianist. He performed throughout Europe and was considered one of the leading pianists of his time. Brahms died in Vienna in 1897.
So, to answer your question, Johannes Brahms did indeed play an instrument. He was a talented pianist, violinist and cellist.