There's alot of questions asking for help troubleshooting errors when T_Echo and T_Print arise, but what does the T_ mean?
It stands for "token". PHP source code is split into tokens, then interpreted. This process is known as tokenization.
See this page for a list of PHP tokens.
You can see for yourself how tokenization works by running token_get_all() on a piece of PHP code.
The reason why these often come up in basic troubleshooting questions is that the OP has made a syntax error, and the parser encounters an unexpected token as a result of that.