it writes to the file with elevated priviledges and doesn't write it back to the terminal, effectively a 'sudo sh -c '{cmd} > {file}''.
sudo tee is a common way to work around priviledge restrictions in shell pipes (you can't easily 'sudo' a pipe), if /secure was 0600 and owned by root:
"sudo echo "test" > /secure" or "sudo printf '' > /secure", would not work because your user's shell process can't write to /secure. However, "echo 'test' | sudo tee /secure" works because the elevated 'sudo tee' can write to the file.
sudo tee is a common way to work around priviledge restrictions in shell pipes (you can't easily 'sudo' a pipe), if /secure was 0600 and owned by root:
"sudo echo "test" > /secure" or "sudo printf '' > /secure", would not work because your user's shell process can't write to /secure. However, "echo 'test' | sudo tee /secure" works because the elevated 'sudo tee' can write to the file.