What does 'all the phenomena related to the senses are "not real"' mean?

Upasaka Angus asked on [another place](https://buddhism.stackexchange.com/a/33943/11235) : >What do you mean that all the phenomena related to the senses are "not real"? So what does a statement '"all the phenomena related to the senses are "not real (anicca)"' dhammical mean? What are phenomena related to the senses? *(Note that question in Dhamma is not dedicated for trade, exchange, stacks or entertainment but as a means to make merits toward release from this wheel)*