The Ogoh-ogoh monsters symbolize the evil spirits surrounding Balinese environment which have to be got rid of and this happens a day before Nyepi. The Balinese open their New Year in silence. This is called Nyepi Day, the Balinese day of Silence.
pakec
CC BY 2.0
<a rel="nofollow" class="external free" href="https://www.flickr.com/photos/pakec/2345470402/">https://www.flickr.com/photos/pakec/2345470402/</a>