This is the 9259th most frequent Russian word.
социальные
"Social."
Here, 'социальные' specifies 'сети' (networks) as related to society or enabling social interaction between people.
Социальные сети помогают людям общаться.
Social networks help people communicate.
In this sentence, 'социальные' modifies 'проблемы' (problems), describing them as issues affecting society or its members broadly.
Государство должно решить социальные проблемы.
The state must address social issues.
Here, 'социальные' refers to 'эксперименты' (experiments), indicating their focus on studying societal behaviors or interactions.