title: Figuring out an array formula syntax
body: <p>Does anyone know what this does and explain it to me?</p>
  
  <pre><code>=ARRAYFORMULA(ARRAY_CONSTRAIN(MMULT(N(REGEXMATCH(
   TRANSPOSE('Form Responses 1'!C2:C),B2:B)),N(IFERROR(
   (EOMONTH('Form Responses 1'!B2:B,-1)+1=A2))*IFERROR(
   LEFT('Form Responses 1'!D2:AU,FIND(" ",'Form Responses 1'!D2:AU)-1)))),
   COUNTA(B2:B),COUNTA(G1:AU1)))
  </code></pre>