COUNTIF lets you count data based on a specific criterion. COUNTIFS works for multiple conditions. Check out the following real-life counting spreadsheet formulas.
Learn a detailed tutorial on the use of QUERY and IMPORTRANGE to import data from spreadsheets with conditions.
Is Google Sheets Query function difficult to understand? Read this blog post to discover the secrets of the Google Sheets Query function syntax through easy to understand formula descriptions and real examples accessible from a view-only spreadsheet.
Can the IFS function replace nested IF statements used with logical operators AND and OR? Check this out through real formula examples.
IMPORTDATA is the way to manually fetch CSV data into Google Sheets. Check out the tutorial to learn an alternative way to automate data import.
Review this blog post to learn how to link data between Google Sheets by utilizing different approaches, and pick the one that will suit you the best.