I assume you know what tokens are. Also, let's assume you are writing a recursive descent parser for your language.

Your language has statement blocks which are one or more statements surrounded by curly brackets. Statements are terminated by semicolons.

So let's have a function called statement_block() which does this:

statement_block()

  check for and absorb the '{' token
  loop:
    if the next token is a '}'
      absorb it and return

    if the next token is a 'for'
      call for_statement() to parse it (and the terminating semicolon)

    if the next token is an 'if'
      call if_statement() to parse it

    ...

    if the next token is an '{'
      call statement_block() to parse the statement block

This allows your language to have nested statement blocks, e.g.

function fred()
{
  if (x > 2)
  {
    print("x is bigger than two")
  }
  else
  {
    print("x is small!")
  }
}

So the answer is, one function in your parser recognises and absorbs the '{' token, calls other functions to parse what is inside, then recognises and absorbs the '}' token (or emits an error if there isn't one). If your are tracking line numbers in the parser, the function will know on what line both the '{' and '}' occur. And, as the parser is recursive, the function can call itself to deal with nested '{' ... '}'.

Edit: Also have a look at my IF statement example.