What does Nehemiah 8:15 mean?

They were supposed to announce and spread the word in all their towns and in Jerusalem: 'Go out to the hills and bring back branches from olive, wild olive, myrtle, palm, and other leafy trees to make shelters, as it's written.' Nehemiah 8:15 - Modern Text Bible

(The people are called to actively participate, gathering materials and building shelters as a sign of obedience.)