It means 'enjoying it very much'.

This is a case where a verb which is usually a stative verb ( describing a constant state) can be used as a dynamic verb (describing a temporary 'activity').

Using present continuous for narrative purposes lends immediacy -- it's happening now, emphasis on NOW ... 

I'd argue the example you have<em> is</em> a narrative use...

For example --

1) In the same way that sportscasters use present continuous to deliver step-by-step detailed descriptions of what is happening. In a hockey game, for example -- he is moving down the ice, he passing the puck to Avery, who is waiting on the blue. They're moving fast. Now, Johnson is coming up from the centre line

2) Also used when news reporters are doing live reports ... we are waiting to hear results about ... the police are arriving and we're being told that ... crowds are gathering and people are being told ...

One of the uses of present continuous is to lend immediacy i.e. it's not habitual e.g. "I love this class"

"I love this class" (present simple) would be always, usually, normally

In the case of "I'm loving XYZ" the speaker is emphasizing that his feeling is <em>NOW</em>, it's this summer, this week, this afternoon, right now ... maybe something that happened THAT DAY caused the speaker to say "I am loving this class" (the implication, too, is that it is <em>temporary</em>, it could change)

e.g. I'm loving my life in a village (but it's boring here and so, I might move soon)

vs I love my life in a village (that's a fact, it's usual) no implication that it might be temporary 

thanks for both of your help