Piano learners tend to forget about phrasing. Or I should rather say that they don't know the importance of phrasing. And it's easy for piano players to ignore the phrasing more so than woodwind players, brass players, and singers. Why? Because singer, woodwind players, and brass players all need to use their breath to phrase the music. So, it's very natural for them to coordinate their breath and the music they are creating.
On the other hand, piano players (if they are especially beginners or intermediate) think that they can play piano without concerning about phrasing. They can just strike keys with their fingers. And the sound comes out. But that kind of playing won't create music. It's going to sound rather mechanical, robotic, unnatural. It's just like typing fonts.
In music, phrases are musical sentences. You need to flow nicely from one sentence to the next, meaning one musical phrase to the next musical phrase. Let me give you an example. First, read this paragraph I've just created out loud.
"I've just come back from Hawaii. I was there with my family for a week. It was wonderful. We saw a whale and turtle. The weather was perfect. The food was great. A lot of flowers. I want to go back there again soon."
Ok. Now, I'm going to "type" this paragraph just like a piano student who doesn't know anything about musical phrasing. The 1st example goes:
"i ve just co me back from ha wa ii i was the re with my fa mi ly for a we ek it was won der ful we saw a wha le and tur tle the wea ther was per fe ct the food was great a lot of flo wers i want to go back the re a gain so on"
No accent anywhere. No ups and downs. It's completely flat. Too many breaks. Very choppy. You can't tell where a sentence starts and end.
Now, I'm going to give you another example:
This time, no break at all for a speaker to take a breath. No ups and downs. No accent. It's completely flat. And it's very stifling.
You can imagine how these two examples above sound like. You can try them now. I'm sure you would laugh. You can easily guess the listeners have no idea what you are trying to say. The same happens with piano players who don't care about phrasing the music. They are going to sound like one of these 2 or combination of both. And the audience won't understand your musical expression. This kind of "typing" music won't reach the audience's heart at all.
If you haven't thought about musical phrasing on the piano before, now you understand how important it is to incorporate phrasing into your piano playing. The best way to find your musical phrasing is to sing each phrase. And right before you play (or sing) the next phrase, take a breath, just like when you take a breath quickly to say the next sentence. Let your fingers speak, just like your voice.