Hi Adrian Gawryszewski,

Thanks for the reply and then I would say sorry because I was busy with some other things so did'nt get chance to respond you back.
Let me share some of my code with you :

Demo.cmp
<aura:component controller="DemoPageController" implements="force:appHostable">
    <aura:attribute name="accounts" type="account"/>
    <aura:handler name="init" value="{!this}" action="{!c.doInit}" />
    <div class="slds">
        <fieldset class="slds-form--compound">
            <div class="form-element__group">
                <div class="slds-form-element__row">
                    <div class="slds-form-element slds-size--1-of-2">
                        <label class="slds-form-element__label" for="input-01">Name</label>
                        <ui:inputText class="slds-input" value="{!v.accounts.Name}"/>
                    </div>
                </div>
            </div>
        </fieldset>
        <div class="slds-form-element__row slds-p-top--small">
            <input type="button" value="Save" class="slds-button slds-button--brand"
                   onclick="{!c.submit}"/>
        </div>
    </div>
</aura:component>

DemoController.js

({
    doInit : function(component, event, helper) {
        helper.getAccounts(component);
    },
    
    submit : function(component, event, helper) {
        var newAccRec = component.get('v.accounts');
        console.log(newAccRec);
        helper.save(component, newAccRec);
    },
})

DemoHelper.js

({
    getAccounts: function(component) {
        var action = component.get("c.getAccounts");
        action.setCallback(this, function(response) {
            var state = response.getState();
            if (component.isValid() && state === "SUCCESS") {
                component.set("v.accounts", response.getReturnValue());
            }
        });
        $A.enqueueAction(action);
    },
    
    save : function(component, newAccRec) {
        var action = component.get("c.saveRecord");
        action.setParams({
            "accountRecord": newAccRec
        });
        action.setCallback(this, function(response) {
            var isSaved = response.getReturnValue();
            if (isSaved) {
                console.log('record saved '+isSaved+' and execution ends...');
            }
            else
                console.log('record saved false and execution ends...');
        });
        $A.enqueueAction(action);
    },
})

DemoPageController.apxc

public class DemoPageController {
    @AuraEnabled
    public static Account getAccounts() {
        return new account(name = 'test light account');
    }
    
    @AuraEnabled
    public static boolean saveRecord(Account accountRecord) {
        system.debug('@apex save...' + accountRecord);
        return true;
    }
}

This above mentioned code is supposed to be worked to save a new account record in sf database.

I'm using this in SF classic as given below -:

DemoPage.vfp

<apex:page sidebar="false">
    <apex:stylesheet value="{!URLFOR($Resource.SLDS0121, 'assets/styles/salesforce-lightning-design-system-vf.css')}" />
    <apex:includeLightning />
    <div id="containerLight">
        <div id="Lightning"/>
    </div>
    
    <script>
        $Lightning.use("c:DemoApp", function(){
            $Lightning.createComponent("c:Demo",{},"Lightning",function(cmp){
                
            });
        });
    </script>
</apex:page>


Please look at this and let me know if you have any solution for this. thanks in advane :)