The word reirá is the future form of reír in the third person singular.
See the full reír conjugation

reír

La gente se reirá de ti, y de todos nosotros
People will laugh at you, and at all of us.
Hazle a un Dragón esa pregunta y se reirá.
Ask a Dragon that question and he will laugh.
Porque la gente... no se reirá de ti.
Because the people... they won't be laughing at you.
De hecho, hasta el Guardian se reirá de usted.
In fact, even The Guardian will laugh at you.
Cuando vuelva, nadie se reirá de mí.
When I go back, no one will laugh at me.
Si yo lo dejó ir ahora, el mundo se reirá de mí.
If I let him go now, the world will laugh at me.
Porque la policía se reirá de usted.
Because the police will just laugh at you.
Mucha gente se reirá de tu sueño.
Lot of people will laugh on your dream.
¿Crees que la gente se reirá de ti cuando hagas esto?
Think people are gonna laugh at you when you do this?
La gente se me reirá si saco esto.
People will laugh at me if I pull this out.
Me tropezaré y todo el mundo se reirá de mí.
I'm going to trip and everyone's going to laugh at me.
Aquí la policía solo se reirá de ti.
The local police will only laugh at you here.
Oh, y promete que se reirá fuertemente de todas de ellas.
Oh, and she promises she will laugh heartily at all of them.
En caso contrario, el sol se reirá de ti.
Otherwise the sun will be laughing at you. Yes, yes.
No, no. Es "Rie, y el mundo reirá contigo".
No, no. It's "laugh, and the world laughs with you."
Si las echamos a la calle, la gente se reirá de nosotros.
If we throw them out on the street, people will laugh at us.
Se reirá de mí, pero difícilmente he estado en un pub.
You'll laugh at me, but I've hardly ever been in a public house.
Y nadie se reirá esta vez.
And no one will laugh this time.
Ríe, y el mundo reirá contigo.
Laugh, and the world laughs with you.
¿Está seguro que no de reirá de mi?
Are you sure you won't laugh at me?
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