Exon:These are sequences within primary transcripts that remain after processing and become part of mature mRNA - akin to key scenes kept during movie editing.
Intron: These are sequences within primary transcripts removed during processing - comparable with unnecessary scenes cut out during movie editing.
Splicing:This is the process by which introns are removed and exons joined together in primary transcripts - just like how film editors splice together different scenes to create a coherent movie.