Reduce the side-bearings of glyphs so that there is at least a few funits of overlap.
When a font is used, justification of text may add spacing between letters even if there is none in the font design.
I am unfamiliar with Arabic, but the screen shot shows the overlap in the Glyph Edit Window for some Arabic glyphs in the Arial Regular typeface.
first
thank you
second
my English language no good but I hope understand you
There does not seem to be any overlap for your glyphs 1,2,3,4.
The side bearings should be negative — about -10 funits at least.
If you can attach your font project file (*.fcp) it may help.
thank you
my font :
The font is licensed to Monotype Corporation, so I had to remove the link to your download.
how can help you to help me
Sorry, but removing the license fields just makes it worse. Someone may try to help you, but we cannot allow you to provide links to copyright fonts. The license for Arial does not allow you to modify it. Look for an OpenSource alternative to develop your font editing skills.