Voy al parque.
English: I go to the park.
In Spanish, 'al' and 'del' are contractions. They are formed by combining the prepositions 'a' (to) and 'de' (of/from) with the article 'el' (the, masculine singular).
Use 'al' when you want to say 'to the' before a masculine singular noun. Use 'del' when you want to say 'of the' or 'from the' before a masculine singular noun.
Voy al parque.
English: I go to the park.
El libro es del profesor.
English: The book is the teacher's (of the teacher).
Camino al trabajo.
English: I walk to work.
La casa está cerca del río.
English: The house is near the river.