Can someone please explain this Bluetooth Antenna Test Result, I am new to RF?
Curves in the left are two different presentations how the reflection factor seen by the feeding circuit depends on frequency. The yellow curve is the standing wave ratio which is calculated from the absolute value R of the reflection factor with formula SWR= (1+R)/(1-R). It's not measured directly, it's calculated. You should see that it's quite near 1 at 2,45MHz. Perfect "in tune" value would be SWR=1 which happens if R=0.

The blue curve is in decibels how much the reflection is when it's compared to full mismatch R=1. At 2.45GHz the reflection is the lowest, but it's not perfect (= minus infinite decibels) 

The blue curve is what's measured in the analyzer directly. 100 years ago the measuring equipment of today was unknown, people tried to measure the SWR from the transmission lines. Presenting the reflection factor as SWR has stayed as a tradition.

The shapes and the table in the right present how much the antenna radiates to different directions. The numbers are power intensities compared to the idealized lossless isotropic antenna. 

Antennas generally have strong currents due the non-radiating resonances ie. quite strong local magnetic and electric fields occur without being a part of the radiating wave, they only oscillate locally and induce AC currents to the metal parts and isolation materials. Their resistive losses are seen as decreased efficiency.