...Ahí es nada...

[Quaeso]

-Sí, señor; yo le digo todo. Él me pregunta cómo es una estrella, y yo se la pinto de tal modo hablando, que para él es lo mismito que si la viera. Yo le explico todo, cómo son las yerbas, las nubes, el cielo, el agua y los relámpagos, las veletas, las mariposas, el humo, los caracoles, el cuerpo y la cara de las personas y de los animales. Yo le digo lo que es feo y lo que es bonito, y así se va enterando de todo.

-Veo que no es flojo tu trabajo. ¡Lo feo y lo bonito! Ahí es nada... ¿Te ocupas de eso?... Dime, ¿sabes leer?

-No, señor. Si yo no sirvo para nada. -Marianela cap. III

"Yes—I tell him everything. He asks me what a star is like, and I tell him all about it in such a way that it is the same to him as if he could see it. I explain it all—what the planets are like, and the clouds, and the sky, and the water, and the lightning, the weather-cocks, the butterflies, the mists, the snails, and the shapes and faces of men and animals. I tell him what is ugly and what is pretty, and so he gets to understand everything."

"I see; your work is no trifle. What is ugly and what is pretty! There is nothing.... You decide upon that question? Tell me, can you read?"

"No, Señor.—I tell you I am good for nothing."

Hola, ¿qué significa esta frase: "Ahí es nada"? ¿Quiere decir: "Ahi (¿Hay?) es nada [más difícil de decir que lo que sea bonito y lo que sea feo]"?

[Rusty]

Ahí means 'there'. It's an adverb of place, just like its cousins allí and allá.
Ahí and hay aren't pronounced the same way, nor do they have the same meaning.

Each adverb of place mentioned above has a slightly different meaning, indicating distance from the speaker.
Ahí = nearest the speaker, and allá = farthest away from the speaker.

That said, «Ahí es nada» is an expression used in Spain that expresses admiration. A suitable translation might be "Wow!" or "That's not easy!"

[Quaeso]

Entiendo, gracias.