Huesos literally translates to "bones". While a common word, its use in this song is a powerful and dramatic metaphor for absolute devotion.
Shakira sings, "Yo te doy hasta mis huesos" (I give you even my bones), to show she's willing to give her lover everything she has to make them stay. This visceral and hyperbolic statement is an unforgettable way to express all-consuming love, making it a fantastic word to learn.
This is a song about being so in love that you'd give the other person absolutely everything you have. Shakira starts by offering her body and affection with lines like, "Te regalo mi cintura / Y mis labios para cuando quieras besar" (I give you my waist / And my lips for when you want to kiss). But she doesn't stop there. She offers her personality, her flaws, and even her thoughts, promising, "Te regalo mi locura / Y las pocas neuronas que quedan ya" (I give you my madness / And the few neurons I have left). She's basically saying, "I'll give you my whole self, just please don't leave me."
The chorus explains why she's so desperate. This person is her entire world: "Porque eres tú mi sol / La fe con que vivo" (Because you are my sun / The faith I live with). The love is so intense that it becomes a little extreme. She sings that if her lover ever decided to leave again, "Cerraría cada puerta / Para que nunca pudieras salir" (I would close every door / So you could never get out). It's a powerful and dramatic way to say she can't imagine her life without this person.