eric@dev ~ $ php a.php
PHP Parse error: syntax error, unexpected T_VARIABLE in
/home/el/code/a.php on line 3
Explanation:
The PHP parser converts your program to a series of tokens. A T_VARIABLE is a Token of type VARIABLE. When the parser processes tokens, it tries to make sense of them, and throws errors if it receives a variable where none is allowed.
In the simple case above with variable $b, the parser tried to process this:
$a = 5 $b = 7;
The PHP parser looks at the $b after the 5 and says "that is unexpected".