This is the 475th most frequent Croatian word.
svemu
"Svemu" means "to everything" or "to all" in English.
The word 'svemu' serves as the dative case of the word 'sve' (everything), used here as the object of the verb 'vjerovati'.
Vjerujem svemu što mi kažeš.
I believe everything you tell me.
In this sentence, 'svemu' is again the dative case of 'sve', paired with the verb 'razumjeti' to indicate to what the understanding applies.
Razumijem svemu kad mi polako objasniš.
I understand everything when you explain it to me slowly.
Here, 'svemu' is used in its dative case to highlight the recipient of the situation or state described by 'je kraj' (comes to an end).