Learn Spanish (Latin America): Engañar al consumidor es lo que crea el problema. - Deceiving the consumer is what creates the problem.

Here, lo que translates to "what" in the sense of "that which" or "the thing that." You need the neuter pronoun lo because it refers back to the entire preceding clause—the abstract idea of "deceiving the consumer" (engañar al consumidor)—rather than pointing back to a specific masculine or feminine noun. It doesn't have an accent mark (qué) because it is a relative pronoun, not a question word.

Why does the sentence start with the infinitive Engañar instead of a gerund like Engañando for "Deceiving"?

In Spanish, when an action is used as a noun (such as the subject of a sentence), you must always use the infinitive, which is engañar here. While English often uses the "-ing" form ("Deceiving the consumer..."), Spanish literally says "To deceive the consumer..."

Why is there an al before consumidor?

This is a combination of the personal a and the article el. Because the consumer (consumidor) is a person (or a specific group of people) and is the direct object receiving the action of engañar (to deceive), Spanish requires the personal a. When a is followed by el, they merge into the contraction al.

What subject is the verb crea (creates) agreeing with?