This is the 5928th most frequent Russian word.
сайтов
The Russian word "сайтов" means "websites" (genitive plural form).
In this sentence, 'сайтов' is used in the genitive plural form, indicating possession or relation to website development.
Я занимаюсь разработкой сайтов.
I specialize in website development.
Here, 'сайтов' is again in the genitive plural form, showing the possessive relation—specifically the design belonging to the websites.
Дизайн этих сайтов очень современный.
The design of these websites is very modern.
In this case, 'сайтов' is used in the genitive plural form to complement 'разнообразие,' a noun requiring the genitive case to signify the type of variety.