Learn Italian: Non distinguo il contorno del quadro e non ci capisco nulla. - I do not distinguish the outline of the painting, and I don't understand a thing about it.

Adding ci to capire creates the pronominal verb capirci. While capire just means "to understand", capirci is used colloquially to mean "to understand something about a situation or topic" or "to make sense of it". Here, non ci capisco nulla essentially means "I can't make head or tail of it."

What is the rule for placing ci with the double negative non ... nulla?

Clitic pronouns like ci must attach directly to the front of the conjugated verb. The negative particle non always goes before the pronoun, giving the strict order: non + pronoun (ci) + verb (capisco). Finally, the second part of the negation (nulla) immediately follows the verb.

Does contorno del quadro mean the physical frame of the painting?

No. Il contorno refers to the outline, contour, or the shapes within the image itself. If you meant the physical wooden or metal frame hanging on the wall, you would use la cornice. The speaker here is struggling to see the painted shapes clearly, which is why they cannot make sense of the artwork.

How is the -guo in distinguo pronounced?