Learn Spanish (Latin America): No vayas a ese enlace falso.

To give a negative tú (informal 'you') command, Spanish doesn't use the regular present tense (vas) or the positive command (ve). While most negative commands are made by swapping the verb's ending vowel, the verb ir (to go) is totally irregular here. You just have to memorize that 'don't go' is always no vayas.

Why do we need the word a in this sentence?

The verb ir (to go) is almost always followed by the preposition a (to) when you are talking about a destination. Even though clicking a web link doesn't involve physical travel, you are still 'going to' a destination in Spanish, so a is required.

Since 'that' is often eso, why does this sentence use ese?

Eso is a neutral word used for abstract ideas, situations, or unknown objects (like saying 'What is that?'). However, when you put 'that' directly in front of a masculine singular noun like enlace, you must use the masculine adjective form, which is ese.

Enlace ends in '-e'. How do we know it is a masculine noun?