There is no "clear-cut" meaning to Algernon words. Instead, his initial dialogue with Lane is a conglomerate of puns written by Wilde with the purpose of declaring, from the very start of the play, what his intentions are with it. These intentions, as it is soon known, are not to present a typical Shavian-type comedy of manners. Instead, his true aim is to generate controversy by making all that is meant to be serious and meaningful to his peer Victorians into silly and comical.
According to several Wilde scholars, the first part of The Importance of Being Earnest fully succeeds at introducing the audience to the central theme of the plot, triviality, and to the satirical mood of the play. Everything that Algernon says and does in this first part of the play not only mocks the Victorian middle classes (and their system of values) but also sets the atmosphere of what will become a completely non-sensical story that, in the end, will make even less sense... by turning out to be true.
The way that Wilde creates this effective set up is by having Algernon speak in semantic layers designed to annoy his "haters": the middle-class righteous Victorians whom openly criticized and mocked him in many newspapers. Notice how the dialogue develops:
I don't play accurately-any one can play accurately- but I play with wonderful expression.
Here Algernon throws a pun at the Victorian need for exactness and formality. To cite that it is better to have expression than accuracy is a pun that hints at Wilde's own dislike for the tendencies of the society in which he lived. Hence, from the very start it is clear in the play that instinct, and all that comes with it, will supersede reasoning and common sense.
As far as the piano is concerned, sentiment is my forte. I keep science for Life.
Another pun. The piano was very powerful object in Victorian society. It was like the Victorian version of a television, or a video game. It brought people together and knowing how to play it would give you a lot of standing in your social gatherings. If you think about Mary Bennett in Pride and Prejudice , the piano was the maker or breaker of the true Victorian; to know how to play the piano was a must.
Yet, here comes Algernon again devaluing another important Victorian icon. Who cares about playing the piano properly? Life is not about rules, but about sensations. This the basic Wildean gist: anything that is of value to the typical Victorian must, by default, be unnecessary and ridiculous.
And speaking of the Science of Life, have you got the cucumber sandwiches cut for Lady Bracknell?
The third powerful pun of the list, Wilde's mischievous want for connecting "the science of life" to a cucumber sandwich was perhaps a last straw that to the modern reader may not mean much. However, the level of notoriety that Wilde had reached by 1895 had earned him a myriad of enemies, for which it was necessary for him to fight back by directly positioning another iconic Victorian social staple, the cucumber sandwich, to a cosmic and ethereal theme of great magnitude, such as it is the science of life. Again, a direct attack is made against the sanctimonious and hypocritical Victorians who openly detested Wilde and his work by mocking their way of life and the importance that they give to everything that is really not important. Hence, the name of the play.