This is the 89th most frequent Czech word.
strany
"Strany" in Czech means "sides" or "parties" (context-dependent).
In this sentence, 'strany' refers to spatial sides, meaning physical locations on either side of the river.
Na obou stranách řeky rostou vysoké stromy.
On both sides of the river, tall trees grow.
Here, 'strany' is used in the singular form 'straně' referring to a page in the brochure, indicating a section of a printed document.
Projděte si pokyny na první straně této brožury.
Review the instructions on the first page of this brochure.
In this context, 'strany' is used to denote opposing parties involved in an agreement or discussion.