Settings:
• FRAMA: blue line, SC = 252, FC = 40 , length = 252
• EMA: orange line, length = 50

FRAMA seems to be the evolution of the current and much-used EMA . The basic strategy is simple: long if the price crosses up the line, short or exit if vice versa.
The main difference between EMA and FRAMA is that the first one seems to lag much more than the first one, as we can see from the chart below ( crude oil daily chart )

FYI

//@version=2

price = close
len = input(defval=252,minval=1)
FC = input(defval=40,minval=1)
SC = input(defval=252,minval=1)

w = log(2/(SC+1))
len1 = len/2
H1 = highest(high,len1)
L1 = lowest(low,len1)
N1 = (H1 - L1)/len1

H2 = for i = len1+1 to len
high>high[i]?high:high[i]

L2 = for i = len1+1 to len
low>low[i]?low:low[i]

N2 = (H2 - L2)/len1

H3 = highest(high,len)
L3 = lowest(low,len)
N3 = (H1 - L1)/len

dimen = (log(H1+H2) - log(H3))/log(2)
oldalpha = exp(w*(dimen-1))
oldN = (2-oldalpha)/oldalpha
newN = ((SC-FC)*(oldN-1)/(SC-1))+FC
alpha = 2/(newN+1)
out = nz(out[1])*(1-alpha) + price*alpha

plot(out,title="FRAMA")