Translation:

This is a rhyme that parents, usually moms, will say to their kids when they get a little injury. My informant said that it’s like a mom kissing a boo-boo and that you can hear a lot of Latin mothers say this to their kids; he learned it from his. Sometimes there will be variations on it such as:

“sana, sana, culito de rana,
si no se te alivia ahora,
se te aliviará mañana”

Translation:
it heals, heals, little ass of frog,
if it is not alleviated to you now,
is alleviated to you tomorrow

Sometimes parents will change “ass” to “tail” or “bottom” for little boo-boos and keep it as “ass” for boo-boos that hurt a lot.