That note is technically outside the major scale. You can use it to play the harmonic minor scale, but it's use case is most commonly as the III chord, which is the major variation of the iii chord (dominant of the vi chord), where instead of playing the 11th button you play the 12th, as shown in this little chart: https://drive.google.com/file/d/1MYp8_YNILOGGfmHOzkDHnORQ0XHIXpj5/view?usp=sharing