Alessandro Lindblad (born July 7, 1991), commonly known by his stage name Alesso, is a Swedish DJ and electronic dance music producer. Specializing in progressive house, Alessandro Lindblad achieved worldwide attention and popularity in 2011 with wide support of his original productions and remixes from the likes of Avicii, and other well established DJs. And Tove Ebba Elsa Nilsson (born 29 October 1987), as a young girl, she started writing poetry and short stories, and later on she studied at Rytmus Musikgymnasiun, a music school. Better known by her stage name Tove Lo, she is a Swedish singer, songwriter and musician from Stockholm, Sweden. Tove Lo has also written songs for a number of artists; including Icona Pop, Girls Aloud, and Cher Lloyd among others.

In my opinion the meaning of the song's lyrics it's about two lovers crazy in love who feel the magical power about love. When they're together they're feeling like if they're the only two in world. Both think they're not ordinary humans. They think they're in an other planet, like some heroes who can fly around the sky. Together the ambiance is like a dream. They're out and in the street but with the feeling to be hiding "Got a secret side in plain sight". Alone in the world. With the feeling to be invincible. They've no limits like if they can push out all the rules.

Lyrics:

We could hide away in daylight
We go undercover wait out the sun
Got a secret side in plain sight
Where the streets are empty
That's where we run

Everyday people do everyday things 
But I can't be one of them
I know you hear me now
We are a different kind
We can do anything

We could be heroes
We could be heroes, me and you
We could be heroes
We could be heroes, me and you
We could be...

Anybody's got the power
They don't see it because they don't understand
Spin around and around for hours
You and me, we got the world in our hands

Everyday people do everyday things 
But I can't be one of them
I know you hear me now 
We are a different kind
We can do anything

We could be heroes
We could be heroes, me and you
We could be heroes
We could be heroes, me and you
We could be...

We could be heroes
We could be heroes, me and you
We could be...

All we're looking for is love and a little light
Love and a little light
We could be...
All we're looking for is love and a little light
Love and a little light

We could be heroes
We could be heroes, me and you
We could be...

The song itself explains what makes for a hero. It's not just powers or save somedy on fire or somedy afraid in front of a shark. Instead, what makes the difference it's what we are on our mind and heart. I think two people who are in love can be heroes for each other. With someone to support you in the daily routine the difficulties are easier to overcome.

 https://www.youtube.com/watch?v=a7SouU3ECpU