Apart from being the past participle of hacer, hecho is also a noun, and the commonest way of expressing the idea of a fact:
Es un hecho conocido. It’s a well-known fact.
In its meaning of fact you often use hecho to introduce a clause with the structure el hecho de que…
Su éxito se explica por el hecho de que tienen como principio-guía de su actividad el respeto a la vida humana. Their success is explained by the fact that the guiding principle behind their activity is respect for human life.
In the previous example the verb in the clause is in the indicative —tienen— because the writer is making a clear statement about something they perceive to be a fact. Compare that with the following example:
Está impresionada por el hecho de que se pueda inaugurar una pista de hielo sin un material sanitario mínimo. She’s amazed by the fact that they can open an ice rink without basic first-aid equipment.
You don’t only use the subjunctive after verbs, but also in certain kinds of noun clause, such as el hecho de que. In the example above the verb pueda is in the subjunctive because the person concerned is expressing an emotion —impresionada— which is one of the factors dictating that you use the subjunctive.
You often use el hecho es que… the fact is… when you want to express your view of a situation in a forceful way:
El hecho es que ha desaparecido. The fact of the matter is that he’s disappeared.
It can also have practically the opposite meaning. You use it to introduce a statement you’re apologetic about, in which case the translation is the thing is…, or the trouble is…
El hecho es que no voy a poder hacerlo a tiempo. The thing is, I’m not going to be able to do it in time.
El hecho es que no pude encontrarlo en versión española. The trouble is, I couldn’t find a Spanish translation of it.
Come back next week for another insight into Spanish vocabulary!