I don't undersand the following tasks please provide some more details about it.

Weekly Retention Analysis: Objective: Analyze the retention of users on a weekly basis after signing up for a product. Your Task: Write an SQL query to calculate the weekly retention of users based on their sign-up cohort. Weekly Engagement Per Device: Objective: Measure the activeness of users on a weekly basis per device. Your Task: Write an SQL query to calculate the weekly engagement per device. Email Engagement Analysis: Objective: Analyze how users are engaging with the email service. Your Task: Write an SQL query to calculate the email engagement metrics. Please give more information otherwise I will endup loosing my marks for doing wrong thing. Just tell me what is your expectation from this tasks.