Change wording of admin menu item?

Inside the plugin folder check for File: jigoshop_taxonomy.php
Line no: 120

You will see

register_post_type( "product",
    array(
        'labels' => array(
            'name'              => __( 'Products', 'jigoshop' ),
            'singular_name'     => __( 'Product', 'jigoshop' ),
            'all_items'         => __( 'All Products', 'jigoshop' ),
            'add_new'           => __( 'Add Product', 'jigoshop' ),
            'add_new_item'      => __( 'Add New Product', 'jigoshop' ),
            'edit'              => __( 'Edit', 'jigoshop' ),
            'edit_item'         => __( 'Edit Product', 'jigoshop' ),
            'new_item'          => __( 'New Product', 'jigoshop' ),
            'view'              => __( 'View Product', 'jigoshop' ),
            'view_item'         => __( 'View Product', 'jigoshop' ),
            'search_items'      => __( 'Search Products', 'jigoshop' ),
            'not_found'         => __( 'No Products found', 'jigoshop' ),
            'not_found_in_trash'=> __( 'No Products found in trash', 'jigoshop' ),
            'parent'            => __( 'Parent Product', 'jigoshop' )
        ),
        'description'        => __( 'This is where you can add new products to your store.', 'jigoshop' ),
        'public'             => true,
        'show_ui'            => true,
        'capability_type'    => 'post',
        'publicly_queryable' => true,
        'exclude_from_search'=> false,
        'hierarchical'       => false, // Hierarchial causes a memory leak http://core.trac.wordpress.org/ticket/15459
        'rewrite'            => array( 'slug'=> $product_base, 'with_front'=> false, 'feeds'=> $base_slug ),
        'query_var'          => true,
        'supports'           => array( 'title', 'editor', 'thumbnail', 'comments', 'excerpt',/*, 'page-attributes'*/ ),
        'has_archive'        => $base_slug,
        'show_in_nav_menus'  => false,
    )
);

Update it as needed.