The racket the local shop is pushing is probably the one their pro plays. That's almost never the right racket for you. Here's the spec a beginner actually wants.
Head size: 100-110 square inches
A bigger head = bigger sweet spot = more forgiving on off-centre hits. Pros use 95-98 sq in for control. You don't need that yet — 100 to 110 will let you make contact when your timing is wrong (which is most of the time when you're starting). Anything called "oversize" or "midplus" is in the right range.
Weight: 270-285 grams unstrung
Lighter than 270g and the racket gets pushed around by hard incoming balls. Heavier than 290g and your shoulder will hate you after a one-hour lesson. The 270-285g zone is where a beginner adult should sit. Junior models below this exist but they limit power on serve.
String pattern: 16x19, open
A 16x19 (sixteen vertical strings, nineteen horizontal) is the "open" pattern — easier to generate spin, more forgiving, and the standard for beginners and intermediates. Skip 18x20 closed patterns; they're for advanced players who want flat-ball control.
Stiffness and feel: don't overthink
Stiffness ratings (RA 60-72) get debated endlessly online. For a beginner, just avoid the very stiff (above 70) which is hard on the elbow if you mishit a lot — which you will. Anything 62-68 is fine.
Brand and price
At 90-180 euros every major brand (Wilson, Head, Babolat, Yonex, Prince) makes a perfectly good beginner racket. Below 60 euros the material is plastic-y and won't last; above 250 you're paying for spec you can't yet use. Most beginners overspend.
Find a court and ask the coach if they have one or two demo rackets. Hitting twenty balls with each tells you more than any chart.