Hello.
NTA score basically means with your percentile which can be calculated by using the below formula:
NTA score= (100 X total number of candidates appeared in the 'session' who get less than and equal raw score than the candidate.)/total number of candidate appeared in the 'session'.

• In the January session the total number of candidates appeared for the exam are: 869010.
  

Now you get 70 NTA score. That means your total percentile score is 70 now if you want to calculate your rank then it is quite difficult task to numerate your actual rank but you can calculate your approximate rank by using the below formula:
(100-your total percentile score)*869010/100.
Let suppose if the number of candidates appeared in the April session increased to 12,00000 then approximate rank can be calculated by the formula:
(100-your total percentile score)*12,00000/100.
So after the treatment of the first formula your approximate rank at 70 percentile would be: 260,703.
(If we do not consider any category wise rank).
now if you want to predict colleges on the basis of your percentile then you can use our college Predictor tool from the below link:

JEE Main College Predictor 2020 - Predict Colleges ba ...

JEE Main College Predictor – Know your College Admission Chances Based ...

Best of luck