Prepositional phrases give information that describes a verb, subject or object, usually by locating it in time or space.
A Prepositional phrase is built around a preposition. A preposition is a word that shows the relationship between between its object and the word it modifies by locating them in time or space. e.g. "on", "under", "after", "toward", etc.
A Prepositional phrase contains a preposition, an object of the preposition (a noun or pronoun) and (sometimes) adjectives modifying the noun.
It is important to determine which word the phrase modifies. If it modifies the verb, it functions like an adverb. If it modifies a noun, it functions like an adjective.
Prepositional Phrase: [preposition + (modifier(s)) + object] that modifies a verb, subject or object. The Prepositional Phrases are highlighted in the following sentences.
Others, like seed sown on good soil, hear the word, accept it, and produce a crop.   Mk. 4:20
Hint: Prepositional phrases can be located by asking "Where?" and "When?" etc. for verbs and "Which one?" for nouns.
e.g. "Where did he hit the ball?" "Which window?"