La carretera cerca del río tiene muchas curvas.

Del is simply de + el.
• de means “of” or “from”
• el is the masculine singular definite article “the”
Put together, del means “of the” or “from the.”

• Carretera is a feminine noun, so it takes la (“the road”).
• Río is masculine, so it takes el. In the sentence it appears as del río because of the contraction de + el.
Spanish generally requires definite articles before countable, specific nouns.

Tiene comes from tener (“to have”) and attributes a characteristic to the road: “the road has many curves.”
By contrast, hay expresses existence: “there are many curves on the road.” Both are grammatically correct, but
• La carretera cerca del río tiene muchas curvas. focuses on the road’s feature.
• Hay muchas curvas en la carretera cerca del río. just states that curves exist there.

• Muchas is an adjective meaning “many,” used with countable nouns like curvas (curves).
• Muy is an adverb that modifies adjectives or other adverbs (e.g., muy grande, muy rápidamente), not nouns.
So to say “many curves,” you need muchas curvas.

Yes, it’s grammatically correct:
“La carretera tiene muchas curvas cerca del río.”
The meaning stays the same, but the emphasis shifts:
• Original order (location first) highlights where the road is.
• Revised order highlights what the road has before mentioning location.

Yes, depending on context:
• Ruta often means “route” or a designated path—common in Latin America.
• Camino refers to a smaller road or even a trail.
• Autopista is a high-speed highway (often tolled or divided).
Use carretera for a standard paved intercity road; choose the alternative if it better fits the type of road you have in mind.