Its not one single note but of 2 same notes in a voice, which is quite clear because there's one half note and a quarter note. There are many ways to play it. One is just holding the key for the longer duration (that is the half note), or you could hold the notes with both left and right hand (if its feasible depending on the structure) or...
THE METHOD GIVEN BELOW IS A WAY OF FAKING SO YOU MIGHT NOT WANT TO USE IT:
play 2 separate quarter notes, but with a lot of pedal so that it might be hard to distinguish the two notes but not the voices. Hope this helps.