Al pasar por el monte Tepeyac se le aparece la Virgen

Al pasar por el monte Tepeyac se le aparece la Virgen.

What is the right translation of this sentence? And why do we have se le there? What is its meaning?

As he was going through mount Tepeyac, Saint Mary appeared to him

le = to him
“se” (lit. him/herself) is here a part of the verb aparecerse = appear, show up, reveal oneself
Think of it that way: Saint Mary revealed herself (se) to him (le)

Malay: Saint Mary menunjukkan diri(se) kepadanya (le)
Saint Mary ditunjukkan kepadanya
With the meaning of:
Saint Mary muncul kepadanya

In general, there are many such so called reflexive or pronominal verbs in Spanish (and also in French, German or Russian), much more so than in English. The conjugation (in present) would be
Yo me aparezco = I show up /appear
te apareces
Él se aparece
Nosoros nos aparecemos
Vosotros os aparecéis
Ellos se aparecen

In Malay this “se” (and the other pronouns above) literally mean “diri”, but are often used in a similar way to the prefix “ter” and even “di”, as in the translation above

Lovely explanation. I got it. Thank you.
By the way your Malay is clearly good, should you have any question about the language let me know!

Terima kasih!
Saya suka sekali bahasa Melayu. Akan menanyakan awak, jika ada sesuatu yang tidak mengerti.