Se debe trabajar mucho para tener éxito.
One should work hard to gain success.
Se vive muy bien en este pueblo.
You live well in this village./Life is good in this village.
Se busca a los testigos del crimén.
They're looking for witnesses to the crime.
While the above English translations contain one, they, or you, there is no obvious grammatical subject in Spanish. This lack of an obvious subject is a key part of impersonal se constructions; it's what makes them impersonal!
Impersonal Se Formation
In impersonal se constructions, verbs are always conjugated in the third person singular.
Impersonal Se Formula
se + verb in third person singular
Se estudia muy bien en ese café.
That coffee shop is great for studying.
Se trabaja mejor sin distracciones.
It's better to work without distractions.