Hello CV,
thank you for answering, you mentioned that I have to create a record rule for how many record should be visible.
but how can i create a record rule for the record to be shown but can't be edited?

For the security rights you have to assign

 Assign group A with only read permission [1,0,0,0]

Assign group B with all permissions [1,1,1,1]

This permissions are written in ir.model.access.csv file.

For second requirement you have create record rule for group B with the condition for how many records should be visible to particular group.

ex;

 <record id="group_account_invoice" model="res.groups">  
     <field name="name">Billing</field>     
     <field name="category_id" ref="base.module_category_accounting_and_finance"/> 
     <field name="users" eval="[(4, ref('base.user_root'))]"/>      
     <field name="implied_ids" eval="[(4, ref('base.group_user'))]"/>  
 </record>

For reference see this doc: \https://www.odoo.com/documentation/9.0/reference/security.html