It is difficult to clearly state the first computer language, because the machines went through a series of changes and developments. In other words, the programming language was different for every computer.
The first programming language was written in the 1840s by Ada Lovelace. She wrote down the code for assessing Bernoulli numbers with the Analytical Engine. However, her program was only theoretical, and it was never fully implemented. Although many acknowledge her genius, her code is not recognized as the first official computer language.
In the 1940s, Konrad Zuse wrote the first high-level program for an electronic computer. It was called Plankalkul, and it was not implemented until 1998. Given the length of time it took to make Zuse's program functional, the language is not considered as the first programming language.
That honor goes to FORTRAN, which was the first fully functional program for a computer. It was launched in 1957 by IBM.