AllAccounts_MapController.cls

public class AllAccounts_MapController {
    @AuraEnabled
    public static List<Account> getAccList(){
        List<Account> accList = new List<Account>();
        accList = [Select Id, Name, ShippingStreet, ShippingCity, ShippingState,
                   ShippingPostalCode, ShippingCountry From Account 
                  Where ShippingStreet!=null AND ShippingCity!= null AND ShippingState != null
                  AND ShippingPostalCode!= null AND ShippingCountry!=null];
        return accList;
    }
}

Controller.js

({
    init: function (cmp, event, helper) {
        var action = cmp.get('c.getAccList');
        action.setCallback(this, function(response){
            var state = response.getState();
            //alert(state);
            if( state === 'SUCCESS'){
                var responseValue = response.getReturnValue();
                var mapArray = [];
                for(var i = 0; i < responseValue.length; i++){
                    console.log(' responseValue ', responseValue[i]);
                    mapArray.push(
                        {
                                location: {
                                    City: responseValue[i].ShippingCity,
                                    Country: responseValue[i].ShippingCountry,
                                    PostalCode: responseValue[i].ShippingPostalCode,
                                    State: responseValue[i].ShippingState,
                                    Street: responseValue[i].ShippingStreet
                                },
                        
                                icon: 'standard:account',
                                title: responseValue[i].Name
                        }
                    );
                }
                cmp.set('v.mapMarkers', mapArray);
                cmp.set('v.center', {
                    location: {
                        City: 'Denver'
                    }
                });
                
                cmp.set('v.zoomLevel', 4);
                cmp.set('v.markersTitle', 'Salesforce locations in United States');
                cmp.set('v.showFooter', true);
                //cmp.set('v.zoomLevel', 10);
            }
        });
        $A.enqueueAction(action);
    }
})

MapComponent.cmp

<aura:component controller="AllAccounts_MapController" 
                implements="force:appHostable,flexipage:availableForAllPageTypes,flexipage:availableForRecordHome,force:hasRecordId,forceCommunity:availableForAllPageTypes,force:lightningQuickAction" access="global" >
    <!-- attributes -->
    <aura:attribute name="mapMarkers" type="Object"/>
    <aura:attribute name="center" type="Object" />
    <aura:attribute name="zoomLevel" type="Integer" />
    <aura:attribute name="markersTitle" type="String" />
    <aura:attribute name="showFooter" type="Boolean" />
    
    <!-- handlers-->
    <aura:handler name="init" value="{! this }" action="{! c.init }"/>
    
    <!-- the map component -->
    <aura:if isTrue="{!v.mapMarkers.length > 0}">
        <!-- the map component -->
        <lightning:map
                       mapMarkers="{! v.mapMarkers }"
                       center="{! v.center }"
                       zoomLevel="{! v.zoomLevel }"
                       markersTitle="{! v.markersTitle }"
                       showFooter="{ !v.showFooter }" >
        </lightning:map>
    </aura:if>
</aura:component>